On-Screen-Display messages play an important role in consumer electronics products by providing users with interactive information such as menus to guide them through the usage and configuration of the product. Other important features of OSD include the ability to provide Closed Captioning and the display of channel logos.
However, the heightened standard of digital video technology presents an ever increasing problem of generating and displaying OSD messages. For example, there are specific High Definition Television (HDTV) requirements that an HDTV must display up to 216 characters in four (4) "windows" versus the current National Television Systems Committee (NTSC) requirements of a maximum of 128 characters in one "window". These new requirements place severe strains on the decoding/displaying system for television signals, which must decode the incoming encoded data streams and present the decoded data to a display system with minimal delays. Since OSD messages must be displayed (overlaid) with the video data, the microprocessor of the decoding/displaying system must assign a portion of the memory bandwidth to perform OSD functions, thereby increasing the memory bandwidth requirements of a decoding/displaying system and the overall computational overhead.
Thus, a need exists for a method and apparatus for generating On-Screen-Display (OSD) messages without increasing the hardware requirements, e.g., memory bandwidth, of a decoding/displaying system.